SQL Clone
SQLServerCentral is supported by Redgate
Log in  ::  Register  ::  Not logged in

Where's the Phantom Power?

Phantom power, also called Vampire power, is power that's used by electronic devices even though they're powered off. I've also heard it's a big deal with various chargers being plugged into sockets, but their corresponding devices not being attached. For example, a cell phone charger left plugged into a wall should use power (and generate heat) even when the cell phone isn't plugged into it.

My son is a part of some high school groups that advocate peace and environmental awareness. He heard about this at school and came home to leave us this note:

It was pretty funny, and we agreed to work with him and unplug things in the kitchen we weren't using. However it's a pain and I decided to take my Kill-a-Watt and do some investigating. I was pleasantly surprised by the results.

Cell phone charger - My T-Mobile G-1 has a mini-USB plug, so most every charger works with it, including my wife's Blackberry chargers. I measured the load of a few chargers at rest, no cell phone plugged in, and they showed 0 watts (W).

I checked the blender, the electric kettle, and the toaster, all showing 0W when not being run.

This somewhat goes against the advice that I've heard, and even passed on before. I have some longer term tests across a few hours running to see if things change, but for now, it appears to me that the nuisance of unplugging and managing small devices isn't worth the trouble.

A Better close up as well:

The Voice of the DBA

Steve Jones is the editor of SQLServerCentral.com and visits a wide variety of data related topics in his daily editorial. Steve has spent years working as a DBA and general purpose Windows administrator, primarily working with SQL Server since it was ported from Sybase in 1990. You can follow Steve on Twitter at twitter.com/way0utwest


Posted by Jack Corbett on 15 May 2009

Your son left you a blank note?  How'd you know it was from him?

Posted by Steve Jones on 15 May 2009

Doh! Community Server strikes again. I'll take another picture and post it.

Posted by Robert Cain on 20 May 2009

Actually, it makes a lot of sense that the chargers draw 0 power when not in use. In order for the electric circuit to be complete the device (cellphone, Zune, etc) has to be plugged into the charger. If the device is not plugged in, then the circuit is broken and no electricity flows, much like when you turn off a light switch. If the circuit is broken then electricity can't flow, and thus no power is used.

I suppose there may be a few chargers on the market that do use power, but I believe the overwhelming majority are like the ones you or I have, and rely on the device being hooked up in order for current to flow.

Leave a Comment

Please register or log in to leave a comment.